• Journal of Advanced Marine Engineering and Technology
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• 제39권6호
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• pp.662-669
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• 2015

해저 석유생산시스템에서 빈번히 발생하는 왁스집적 문제는 안정적인 석유 생산을 방해하고 높은 비용을 발생시키므로 왁스집적 제어에 대한 관심이 증가하고 있다. 왁스집적 제어를 통한 석유의 유동안정성 확보를 위해서는 왁스집적거동을 신뢰성 있게 예측해야 한다. 이 연구에서는 왁스집적 거동에 큰 영향을 미치는 분자확산, 전단응력효과, 왁스경화 메커니즘을 시뮬레이션 기술에 적용하여 불확실도가 높은 변수인 전단응력계수, 왁스고형물의 공극률, 왁스 열전도도, 분자확산계수와 물과 가스 양이 왁스집적 거동에 미치는 영향에 대한 분석을 단상과 다상 유동 시 층류 유동 조건에서 수행하였다. 그 결과 왁스고형물의 공극률과 분자확산계수가 높아질수록, 전단응력계수가 낮아질수록 왁스집적 두께가 두꺼워지는 것을 확인할 수 있었고 석유의 온도가 왁스집적 위치에 주요하게 영향을 미치는 것으로 판단된다. 물의 양에 따른 왁스집적 시뮬레이션 결과 기존 연구에서 다소 다른 결과들이 존재하나 이 연구 조건에서는 물의 양 40%까지 왁스집적량이 증가하다 감소하는 것을 확인하였고 가스 양이 많아질수록 유체의 액상 내 가벼운 탄화수소 농도 감소로 인해 왁스집적량이 증가하는 것을 파악하였다. 이 연구결과는 향후 현장 또는 현장을 모사한 실험시스템에서의 결과와 시뮬레이션 결과를 매칭하여 해저 유동관에서 왁스집적 거동을 예측하는데 효과적으로 적용될 수 있을 것으로 사료된다.

• Elastomers and Composites
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• 제44권2호
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• pp.106-111
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• 2009

조직공학은 기능을 상실한 인체를 대체하거나 복원하기 위해 인공대체품을 개발하기 위한 중요한 학문이다. 특히, 세포가 자랄 수 있는 지지체 역할을 하는 스캐폴드는 조직공학 연구를 위한 중요한 부분을 차지하고 있다. 그래서, 3차원 조직공학용 스캐폴드 개발을 위한 다양한 제조 방법을 소개하고자 하였다. 스캐폴드의 일반적인 제조방법으로는 염침출법 (solvent-casting particulate-leaching), 염 발포법 (gas foaming/salt leaching), fiber meshes/fiber bonding 법, 상분리법 (phase separation), melt moulding 법, 동결 건조법 (freeze drying)이 있으며, 넓은 표면적을 가진 스캐폴드 개발방법으로 전기방사법이 알려져 있다. 또한, 최근에는 스캐폴드 내부의 균일한 세포의 침투를 유도하기 위해 적당한 공극크기를 조절하고 우수한 공극률을 가진 스캐폴드를 개발하고자 stereolithography (SLA), selective laser sintering (SLS), fused deposition modeling (FDM), 및 3D printing (3DP) 와 같은 다양한 solid freeform fabrication (SFF) 기술이 개발되어지고 있다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 춘계학술대회 논문집 센서 박막재료 반도체재료 기술교육
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• pp.66-69
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• 2002

This paper presents deposition and characterizations of microcrystalline silicon$({\mu}c-Si:H)$ films prepared by hot wire chemical vapor deposition at substrate temperature below $300^{\circ}C$. The $SiH_{4}$ concentration$[F(SiH_{4})/F(SiH_{4})+F(H_{2})]$ is critical parameter for the formation of Si films with microcrystalline phase. At 6% of silane concentration, deposited intrinsic ${\mu}c-Si:H$ films shows sufficiently low dark conductivity and high photo sensitivity for solar cell applications. P-type ${\mu}c-Si:H$ films deposited by Hot-Wire CVD also shows good electrical properties by varying the rate of $B_{2}H_{6}$ to $SiH_{4}$ gas. The solar cells with structure of Al/nip ${\mu}c-Si:H$/TCO/glass was fabricated with single chamber Hot-Wire CVD. About 3% solar efficiency was obtained and applicability of HWCVD for thin film solar cells was proven in this research.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제54권7호
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• pp.308-314
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• 2005

The 2 GHz film bulk acoustic wave resonator(FBAR), one of the most necessary device of the next generation mobile communication system, consisted of solidly mounted resonator(SMR) structure using Brags reflector, was researched in this paper The FBAR applied SiO$_{2}$ and W had large difference of the acoustic impedance to reflector Al to electrode and ZnO to piezoelectric layer. Specially, the FBAR applied the two-step deposition method to improve the c-axis orientation and increase reproducibility of the fabrication device had good performance. The electrical properties of plasma such as impedance, resistance, reactance, $V_{pp},\;I{pp}$, VSWR and phase difference of voltage and current, was analyzed and measured by RF sensor with the variable experiment process factors such as gas ratio, RF power and base vacuum level about concerning the thickness, c-axis orientation, adhesion and roughness. The FBAR device about the optimum condition resulted reflection loss(S$_{11}$) of -17 dB, resonance frequency of 1.93 GHz, electric-mechanical coefficient(k$_{eff}$) of 2.38 $\%$ and Qualify factor of 580. It was seen better qualify than the common dielectric filter at present and expected on business to the filter device of 2 GHz bandwidth with the MMIC technology.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.387-390
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• 2002

This paper presents deposition and characterizations of microcrystalline silicon(${\mu}$c-Si:H) films prepared by hot wire chemical vapor deposition at substrate temperature below 300$^{\circ}C$. The SiH$_4$ concentration[F(SiH$_4$)/F(SiH$_4$).+(H$_2$)] is critical parameter for the formation of Si films with microcrystalline phase. At 6% of silane concentration, deposited intrinsic ${\mu}$c-Si:H films shows sufficiently low dark conductivity and high photo sensitivity for solar cell applications. P-type ${\mu}$c-S:H films deposited by Hot-Wire CVD also shows good electrical properties by varying the rate of B$_2$H$\_$6/ to SiH$_4$ gas. The solar cells with structure of Al/nip ${\mu}$c-Si:H/TCO/g1ass was fabricated with single chamber Hot-Wire CVD. About 3% solar efficiency was obtained and applicability of HWCVD for thin film solar cells was proven in this research.

• 한국세라믹학회지
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• 제42권7호
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• pp.455-460
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• 2005

Deposition of TiN$_{x}$ film was conducted with a DC sputtering technique. The effect of the processing parameters such as substrate temperature, deposition time, working pressure, bias power, and volumetric flowing rate ratio of Ar to N$_{2}$ gas on the resistivity of TiN$_{x}$ film was systematically investigated. Three kinds of substrates, soda-lime glass, (100) Si wafer, and 111m thermally grown (111) SiO$_{2}$ wafer were used to explore the effect of substrate. The phase of TiN$_{x}$ film was analyzed by XRD peak pattern and deposition rate was determined by measuring the thickness of TiNx film through SEM cross-sectional view. Resistance was obtained by 4 point probe method as a function of processing parameters and types of substrates. Finally, optimum condition for synthesizing TiN$_{x}$ film having lowest resistivity was discussed.

• Journal of Information Display
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• 제11권3호
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• pp.109-112
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• 2010

The solid phase compositions and dielectric properties of silicon nitride ($SiN_x$) films prepared using the plasma enhanced chemical vapor deposition (PECVD) technique at a low temperature ($200^{\circ}C$) were studied. Controlling the source gas mixing ratio, R = $[N_2]/[SiH_4]$, and the plasma power successfully produced both silicon-rich and nitrogen-rich compositions in the final films. The composition parameter, X, varied from 0.83 to 1.62. Depending on the film composition, the dielectric properties of the $SiN_x$ films also varied substantially. Silicon-rich silicon nitride (SRSN) films were obtained at a low plasma power and a low R. The photoluminescence (PL) spectra of these films revealed the existence of nano-sized silicon particles even in the absence of a post-annealing process. Nitrogen-rich silicon nitride (NRSN) films were obtained at a high plasma power and a high R. These films showed a fairly high dielectric constant ($\kappa$ = 7.1) and a suppressed hysteresis window in their capacitance-voltage (C-V) characteristics.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.54-54
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• 2011

The demand for low-friction, wear and corrosion resistant components, which operate under severe conditions, has directed attentions to advanced surface engineering technologies. The Filtered Vacuum Arc Cathode Deposition (FVACD) process has demonstrated atomically smooth surface at relatively high deposition rates over large surface areas. Preparation of Ti-Si-C-N nanocomposite coatings on (100) Si and stainless steel substrates with tetramethylsilane (TMS) gas pressures to optimize the film preparation conditions. Ti-S-C-N coatings were characterized using X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, nanoindentation, Rockwell C indentation and ball-on-disk wear tests. The XRD results have confirmed phase formation information of TiSiCN coatings, which shows mixing of TiN and TiC structure, corresponding to (111), (200) and (220) planes of TiCN. The chemical composition of the film was investigated by XPS core level spectra. The binding energy of the elements present in the films was estimated using XPS measurements and it shows present of elemental information corresponding to Ti2p, N1s, Si 2p and C1. Film hardness and elastic modulus were measured with a nano-indenter, and film hardness reached 40 GPa. Tribological behaviors of the films were evaluated using a ball-on-disk tribometer, and the films demonstrated properties of low-friction and good wear resistance.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.309-309
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• 2012

Heteroepitaxial growth remains as one of the continuously growing interests, because the heterogeneous crystallization on different substrates is a common feature in the fabrication processes of many semiconductor materials and devices, such as molecular beam epitaxy, pulsed laser deposition, sputtering, chemical bath deposition, chemical vapor deposition, hydrothermal synthesis, vapor phase transport and so on [1,2]. By using the R.F. sputtering system, ZnO thin films were deposited on graphene 4 and 6 mono layers, which is grown on 400 nm and 600 nm $SiO_2$ substrates, respectively. The ZnO thin layer was deposited at various temperatures by using a ZnO target. In this experimental, the working power and pressure were $3{\times}10^{-3}$ Torr and 50 W, respectively. The base pressure of the chamber was kept at a pressure around $10^{-6}$ Torr by using a turbo molecular pump. The oxygen and argon gas flows were controlled around 5 and 10 sccm by using a mass flow controller system, respectively. The structural properties of the samples were analyzed by XRD measurement. The film surface and carrier concentration were analyzed by an atomic force microscope and Hall measurement system. The surface morphologies were observed using field emission scanning electron microscope (FE-SEM).

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 C
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• pp.1763-1765
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• 2000

This paper presents deposition and characterizations of microcrystalline silicon ($\mu$ c-Si:H) films prepared by hot wire chemical vapor deposition at substrate temperature at 300$^{\circ}C$. The flow rates of $SiH_4$ gas are critical parameter for the formation of Si films with microcrystalline phase. We could obtain $\mu$ c-Si:H with columnar grain structure and volume fraction of 75% without H2 dilution. The electronic properties, hydrogen bonding configurations, and $H_2$ concentration inside the films are also strongly affected by $SiH_4$ flow rate, which is provided in this paper.